Umgama omde ipleyiti ezintathu ukusonga ngasemva inxalenye,1st umgca ukusonga yi 180 °, 3rd umgca ukusonga has 135 °. Isetyenziselwa ukuvula iibhokisi ngokulula. Iplate yebhanti ephezulu edibeneyo edibeneyo kunye noyilo olukhethekileyo inokulungelelaniswa ngokweemfuno zemveliso, inika indawo yokufakwa kwezixhobo ezikhethekileyo zebhokisi.